This invention relates to air conditioning and, in particular, to a flow distributor for providing equal quality refrigerant to each circuit of a multi-circuit evaporator.
The term quality, as herein used, refers to a two phase mixture of expanded refrigerant having a vapor phase and a liquid phase. The quality of the mixture is the per cent by weight of the mixture that is in the vapor phase.
High precision distributors are sometimes used in association with evaporator heat exchangers having multiple flow circuits. The distributors are typically equipped with sharp edge orifices permanently affixed inside the distributor. These devices are relatively complex in design and relatively expensive to manufacture and install. Despite the use of precision machined parts, the flow distribution can, on occasion, be relatively uneven and these devices also tend to be relatively noisy and thus objectionable when used indoors.
In many split refrigeration systems where the evaporator is located indoors, the condenser and the expansion device for throttling refrigerant moving between the condenser and the evaporator are both located out of doors along with the system compressor. The refrigerant line connecting the condenser and the evaporator is thus relatively long and, as a result, the two phase mixture leaving the outdoor expansion device can undergo separation. When splitting the flow into the evaporator circuits, the separated flow can cause uneven quality levels in the evaporator wherein some circuits receive a higher or lower percentages of the gas phase resulting in less than optimum evaporator performance.
In U.S. Pat. No. 5,341,656 there is described an expansion device for use in a heat pump wherein expanded refrigerant is delivered directly into a distributor. The expanded flow leaving the device is initially turned 90.degree. into a radially disposed channel and then empties through a series of sharp edge orifices into the evaporator flow circuits. The flow circuits are located very close to the expansion device so that the two phase mixture leaving the device is not afforded the opportunity to separate before it is delivered into the evaporator flow circuits. Accordingly, the quality of the refrigerant passing through the circuits is relatively constant. However, as noted above, in split refrigeration systems where the expansion device is located out of doors, the two phase expanded refrigerant must travel a good distance through the refrigeration line before reaching the distributor. As a result, the liquid phase can separate from the vapor phase thus adversely effecting the operation of the downstream evaporator.